| java.lang.Object | ||
| ↳ | java.io.InputStream | |
| ↳ | java.io.FileInputStream | |
 Known Direct Subclasses
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Known Indirect Subclasses
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An input stream that reads bytes from a file.
Developers
File file = ...
InputStream in = null;
try {
in = new BufferedInputStream(new FileInputStream(file));
...
finally {
if (in != null) {
in.close();
}
}
}
This stream is not buffered. Most callers should wrap
this stream with a BufferedInputStream.
Use FileReader to read characters, as opposed to bytes, from a
file.
| Public Constructors | |||||||||||
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Constructs a new
FileInputStream that reads from file.
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Constructs a new
FileInputStream that reads from fd.
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Equivalent to
new FileInputStream(new File(path)).
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| Public Methods | |||||||||||
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Returns an estimated number of bytes that can be read or skipped without blocking for more
input.
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Closes this stream.
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Returns a read-only
FileChannel that shares its position with
this stream.
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Returns the underlying file descriptor.
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Reads a single byte from this stream and returns it as an integer in the
range from 0 to 255.
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Reads up to
byteCount bytes from this stream and stores them in
the byte array buffer starting at byteOffset.
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Skips at most
byteCount bytes in this stream.
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| Protected Methods | |||||||||||
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Ensures that all resources for this stream are released when it is about
to be garbage collected.
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[Expand]
Inherited Methods | |||||||||||
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From class
java.io.InputStream
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From class
java.lang.Object
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From interface
java.io.Closeable
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From interface
java.lang.AutoCloseable
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Constructs a new FileInputStream that reads from file.
| file | the file from which this stream reads. |
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| FileNotFoundException | if file does not exist.
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Constructs a new FileInputStream that reads from fd.
| fd | the FileDescriptor from which this stream reads. |
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| NullPointerException | if fd is null.
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Equivalent to new FileInputStream(new File(path)).
| FileNotFoundException |
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Returns an estimated number of bytes that can be read or skipped without blocking for more input.
Note that this method provides such a weak guarantee that it is not very useful in practice.
Firstly, the guarantee is "without blocking for more input" rather than "without blocking": a read may still block waiting for I/O to complete — the guarantee is merely that it won't have to wait indefinitely for data to be written. The result of this method should not be used as a license to do I/O on a thread that shouldn't be blocked.
Secondly, the result is a conservative estimate and may be significantly smaller than the actual number of bytes available. In particular, an implementation that always returns 0 would be correct. In general, callers should only use this method if they'd be satisfied with treating the result as a boolean yes or no answer to the question "is there definitely data ready?".
Thirdly, the fact that a given number of bytes is "available" does not guarantee that a read or skip will actually read or skip that many bytes: they may read or skip fewer.
It is particularly important to realize that you must not use this method to
size a container and assume that you can read the entirety of the stream without needing
to resize the container. Such callers should probably write everything they read to a
ByteArrayOutputStream and convert that to a byte array. Alternatively, if you're
reading from a file, length() returns the current length of the file (though
assuming the file's length can't change may be incorrect, reading a file is inherently
racy).
The default implementation of this method in InputStream always returns 0.
Subclasses should override this method if they are able to indicate the number of bytes
available.
| IOException |
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Closes this stream. Concrete implementations of this class should free any resources during close. This implementation does nothing.
| IOException |
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Returns a read-only FileChannel that shares its position with
this stream.
Returns the underlying file descriptor.
| IOException |
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Reads a single byte from this stream and returns it as an integer in the range from 0 to 255. Returns -1 if the end of the stream has been reached. Blocks until one byte has been read, the end of the source stream is detected or an exception is thrown.
| IOException |
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Reads up to byteCount bytes from this stream and stores them in
the byte array buffer starting at byteOffset.
Returns the number of bytes actually read or -1 if the end of the stream
has been reached.
| IOException |
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Skips at most byteCount bytes in this stream. The number of actual
bytes skipped may be anywhere between 0 and byteCount. If
byteCount is negative, this method does nothing and returns 0, but
some subclasses may throw.
Note the "at most" in the description of this method: this method may choose to skip fewer bytes than requested. Callers should always check the return value.
This default implementation reads bytes into a temporary buffer. Concrete subclasses should provide their own implementation.
| IOException |
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Ensures that all resources for this stream are released when it is about to be garbage collected.
| IOException | if an error occurs attempting to finalize this stream. |
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